Biopolymer Chitosan Research Articles

Biopolymers as a Potential Alternative for the Retention of Pollutants from Vinasse: An In Silico Approach.

Vinasse, a waste from the bioethanol industry, presents a crucial environmental challenge due to its high organic matter content, which is difficult to biodegrade. Currently, no sustainable alternatives are available for treating the amount of vinasse generated. Conversely, biopolymers such as cellulose, carboxymethylcellulose, and chitosan are emerging as an interesting alternative for vinasse control due to their flocculating capacity against several organic compounds. This study seeks to determine the thermodynamic behavior of in silico interactions among three biopolymers (cellulose, carboxymethylcellulose, and chitosan) regarding 15 organic compounds found in vinasse. For this, the Particle Mesh Ewald (PME) method was used in association with the Verlet cutoff scheme, wherein the Gibbs free energy (ΔG) was calculated over a 50 ns simulation period. The findings revealed that cellulose showed a strong affinity for flavonoids like cyanidin, with a maximum free energy of -84 kJ/mol and a minimum of -55 kJ/mol observed with phenolic acids and other flavonoids. In contrast, chitosan displayed the highest interactions with phenolic acids, such as gallic acid, reaching -590 kJ/mol. However, with 3-methoxy-4-hydroxyphenyl glycol (MHPG), it reached an energy of -70 kJ/mol. The interaction energy for flavonoid ranged from -105 to -96 kJ/mol. Finally, carboxymethylcellulose (CMC) demonstrated an interaction energy with isoquercetin of -238 kJ/mol, while interactions with other flavonoids were almost negligible. Alternatively, CMC exhibited an interaction energy of -124 kJ/mol with MHPG, while it was less favorable with other phenolic acids with minimal interactions. These results suggest that there are favorable interactions for the interfacial sorption of vinasse contaminants onto biopolymers, indicating their potential for use in the removal of contaminants from the effluents of the bioethanol industry.

Novel chitosan-ionic liquid immobilized membranes for PEM fuel cells operating above the boiling point of water

Novel chitosan (CS) composite membranes modified with ionic liquids (ILs), namely, 1-Hexyl-3- methylimidazolium tricyanomethanide ([HMIM][TCM]), Diethylmethylammonium methanesulfonate ([DEMA][OMs]), were synthesized to be used as a polymer electrolyte membrane (PEM) in for PEM fuel cells. The ionic conductivities of the prepared membrane samples were evaluated using electrochemical impedance spectroscopy (EIS). The CS is one of the attractive choices of green and sustainable membrane materials in PEMs because of its chemical tunability and cost-effectiveness. The membranes were prepared by solution casting followed by a solvent evaporating procedure. The low proton conductivity of pristine CS biopolymer was enhanced by the incorporation of ILs in the membrane framework. Tensile testing confirmed the excellent membrane mechanical integrity. A significant enhancement in the membranes’ characteristics was observed upon the introduction of [DEMA][OMs] into its matrix. The experimental results showed enhanced proton conductivities of the prepared membranes along with enhanced flexibility. The proton conductivity of pristine CS membrane was increased from 8.4 × 10−4 to 1.25 × 10−2 S/cm and 1.1 × 10−2 S/cm when a 30 wt% [HMIM][TCM] and 100 wt% [DEMA][OMs] were added, respectively. Synergistic effects of amine and imidazolium-based ILs on the electrical, structural, water uptake, and thermal properties of CS-based biopolymer solid electrolyte membranes are reported for the first time in this work. The aforementioned characterization results demonstrate the potential of using these membranes in PEM fuel cells operating above the boiling point of water and at a lower cost. This work showed that there should be an optimization amount of the ILs content in the membrane to maintain its mechanical integrity.

Biocomposites based on alginate−chitosan−collagen and nimesulide/layered double hydroxides: preparation and characterization

Considering the increase in life expectancy of the world's population, the study of new materials that can act as alloplastic grafts and also have the ability to release drugs directly at the site of the patient's pain is considered of great importance. Therefore, this paper presents a study on synthesizing and characterizing hybrid membranes composed of biopolymers (alginate, chitosan, and collagen) added of zinc and aluminum layered double hydroxides intercalated with nimesulide, a non-steroidal anti-inflammatory drug. These membranes have the potential to be used as resorbable grafts that release the drug in question more slowly. An experimental study was carried out for the synthesis with six variables to define the best composition for synthesizing the membranes. The best condition presented was characterized by XRD, and then a study of the release of nimesulide using UV-Vis spectroscopy was carried out. The XRD technique showed the synthesis of LDH intercalated with nimesulide and its insertion into the polymeric hybrid membrane. The release studies as a function of pH showed that the LDH releases around 20% of the intercalated nimesulide at pHs above 2. At the same time, the membranes contribute to keeping the nimesulide in its protonated form and unavailable to the environment, which contributes significantly, since this membrane, when used as a graft, will fulfill its structural function. As the body absorbs the membrane, it will release the nimesulide at the focus of the patient's pain.

Effect of seed coating in a combination of biopolymer, fungicide and biocontrolagents on the vigour and stem rot incidence of groundnut under in-vitro condition

The experiment was conducted with a combination of effective fungicide, potential biocontrol agents and seed coat biopolymer (chitosan) with different concentrations and their combinations along with untreated seeds as control, were used for coating groundnut seeds. The pathogen was inoculated on each treated and untreated seeds and the maximum germination of 94.0 % was recorded in T5 treatment having double layer seed coat which showed higher vigour index I and II (3190 and 87.4) and minimum seedling mortality of 10.7 %. Whereas untreated seeds (T1 ) showed low germination of 64.0 %, vigour index I and II (1709 and 44.6) with maximum seedling mortality of 75.2 %.

Photocatalytic Efficacy and Degradation Kinetics of Chitosan-Loaded Ce-TiO2 Nanocomposite towards for Rhodamine B Dye

The recent advancement in the production of nanomaterials with novel architectures and functionality has allowed for the effective treatment of industrial wastewaters and contaminated soil and, in that view, the current study aimed to investigate the catalytic efficacy of biopolymer-loaded titanium nanocomposite. Therefore, Cerium (Ce)-titanium dioxide (TiO2) loaded chitosan nanocomposite was formed and studied its catalytic efficacy towards the degradation of an industrial dye pollutant. For the production of Ce-TiO2/chitosan nanocomposite, we followed the hydrothermal synthesis route and the formed nanocomposite was thoroughly analyzed for the crystallinity (using powdered X-ray diffraction, XRD), surface bonding, and nature (using Fourier transform infrared, FTIR spectroscopy), morphology (scanning electron microscopy, SEM), elemental composition (electron diffraction analysis by X-rays, EDAX), porosity (Brunauer–Emmett–Teller, BET), and particles size in powdered form (transmission electron microscopy, TEM). Then the efficiency of synthesized nanocomposite was tested towards the photocatalytic degradation of Rhodamine B (Rh B) dye by applying various parameters such as the irradiation time, solution pH, catalyst dosage, and the dye concentration. Further, the Langmuir–Hinshelwood model was employed to investigate the kinetics of RhB degradation and provided a conceivable photocatalytic mechanism. It was indicated based on the catalyst mechanism that the modification of TiO2 nanoparticles with Ce and loading onto chitosan biopolymer may have accelerated the photocurrent transport due to an increase in the number of electrons and holes generated by the photon’s irradiation. In this way, the study has witnessed the excellent photocatalytic performance of Ce-TiO2/chitosan with 95% Rh B degradation as against the pure TiO2 nanoparticles thus stressing the importance of developing novel composite photocatalysts.

Surface decoration of graphene oxide with tragacanth gum as a promising way to improve the mechanical properties of chitosan nanocomposite; experimental, micromechanical, and simulation study

The interfacial interaction of graphene oxide (GO) with the host polymer is of particular importance in the development of new nanocomposites with ultimate performance. In this perspective, the influence of functionalized GO with the tragacanth gum (TG) polysaccharide on the mechanical characteristic of chitosan (CS) biopolymer was investigated. Spectroscopic and microscopic analysis thoroughly confirmed the TG functionalization process of GO (TG-GO). The understanding of the reinforcement behavior of TG-GO in the host polymer (CS) was constructed by combination of tensile, micro-mechanical/structural testing, as well as molecular dynamic simulation of interfacial interaction. Our finding represented that this functionalization put a remarkable impact on the mechanical properties of CS, which is evident on the microstructure of the fracture surface. The Halpin-Tsai model verified the observed increasing trend in mechanical performance. Simulation results revealed that TG-GO has better interfacial interaction with CS, which is highly in good agreement with the boosted mechanical performance.

A sustainable and eco-friendly approach for environmental and energy management using biopolymers chitosan, lignin and cellulose — A review

Biopolymers are a naturally occurring alternative to synthetic polymers that are linked by covalent bonds, which includes cellular components such as proteins, nucleotides, lipids, and polysaccharides. Based on the extensive literature review it was found that chitosan, lignin, and cellulose were predominantly used in the energy and environmental sectors. Due to their vast array of qualities, including the adsorption, flocculation, anticoagulation, and furthermore, have made them useful for treating wastewater and pollutant removal. Chitosan and lignin have been used as a proton exchange membrane in the energy storage device of fuel cells. As these biopolymers develop strong coordination connections with metal surfaces, they act as an anticorrosive agent, which inhibiting the corrosion. Besides, there are a lot of recent developments in the application of biopolymers for energy and environmental fields. The present review provides a concise summary of recent developments in membrane-based biopolymers role in energy and environmental field. In addition, this review is drawn to a conclusion with a discussion of future trends in the real application of biopolymers in a variety of different industries, as well as the financial significance of these future trends.

Adsorption efficiency of highly methylene blue dye concentrations with multilayer chitosan-modified clays for a precise nanofiltration performance of polluted water

The development of highly efficient non-conventional materials has been a potential solution in water treatment for both environmental and economic reasons. The present work is dedicated to montmorillonite (MMT) with surface modification by biopolymer chitosan at different pH for adsorption of methylene blue (MB) dye. Molecular dynamics (MD) simulations are performed to visualize the adsorption process and unveil the mechanisms at nanoscale. Results show that monolayer and multilayer adsorption of MB tends to occur on the pure MMT and chitosan-modified MMT (CMMT) surfaces, respectively. The mechanism behind the two adsorption modes is controlled by the attraction strength to MB: electrostatic attraction from MMT > intermolecular π–π interactions from dyes > H-bonding interaction from CMMT. Furthermore, to quantify the adsorption capacity and efficiency, an evaluation method for the identification of immobilized dyes based on individual molecular diffusion is proposed for the first time. The immobilization efficiency for MB on CMMT surfaces increases with pH and reaches a maximum value of 80 % (158.79 mg/g) at pH 9.5, assuming that effectively inhibited MB has D < 0.35– 0.95 × 10−9 m2/s. However, the stability of CMMT composites decreases with pH due to the detachment of some chitosan fragments when trapping dye molecules. This study suggests that the CMMT composite is more advantageous than MMT at high dye concentrations and alkaline conditions.

Chitosan in the treatment of mine spoil rainwater - An approach to protect the aquatic biota

The mining industry suppresses vegetation, exposing large soil areas in its ordinary operation. Water pollution and turbidity are caused by the carrying of solids, mainly colloidal particles, to the watercourses due to the effect of rainfall events. Therefore, the discharge of those effluents will lead to failure with watercourse quality parameters. Thus, there is a need to treat drainages (rainwaters) from the mining industry. However, using common coagulants and flocculants can result in acute or chronic ecotoxicity for aquatic biota. In this scenario, this research aimed to evaluate using a natural coagulant, the biopolymer Chitosan, to remove turbidity from mining industry spoiled water through bio-coagulation. The ecotoxicity of the natural coagulant was compared to the commonly used coagulants. For this purpose, we used synthetic rainwater (SRW) from the dispersion of fine (colloidal) particles in natural waters. Materials (water and soil) were collected in the mining area's sumps (sedimentation basins). The turbidity of the produced SRW ranged from between 500 and 4000 NTU. Jar Tests using Chitosan (CTS), polyaluminum chloride (PAC®12), and Superfloc®N100 variable doses were carried out to compare the effects of the coagulating/flocculating agents on the SRW turbidity reduction. The obtained results demonstrated the efficiency of CHS on turbidity reduction. The results were encouraging for low turbidity samples (<1000 NTU), making it possible to meet the limit parameters recommended by the Brazilian legislation. In addition, it was possible to conclude both CHS and the effluents treated with this coagulant have lower toxicity to aquatic biota than the combination of PAC®12 and Superfloc®N100.

Untreated vs. Treated Carbon Felt Anodes: Impacts on Power Generation in Microbial Fuel Cells.

This research sought to enhance the efficiency and biocompatibility of anodes in bioelectrochemical systems (BESs) such as microbial fuel cells (MFCs), with an aim toward large-scale, real-world applications. The study focused on the effects of acid-heat treatment and chemical modification of three-dimensional porous pristine carbon felt (CF) on power generation. Different treatments were applied to the pristine CF, including coating with carbon nanofibers (CNFs) dispersed using dodecylbenzene sulfonate (SDBS) surfactant and biopolymer chitosan (CS). These processes were expected to improve the hydrophilicity, reduce the internal resistance, and increase the electrochemically active surface area of CF anodes. A high-resolution scanning electron microscopy (HR-SEM) analysis confirmed successful CNF coating. An electrochemical analysis showed improved conductivity and charge transfer toward [Fe(CN)6]3-/4- redox probe with treated anodes. When used in an air cathode single-chamber MFC system, the untreated CF facilitated quicker electroactive biofilm growth and reached a maximum power output density of 3.4 W m-2, with an open-circuit potential of 550 mV. Despite a reduction in charge transfer resistance (Rct) with the treated CF anodes, the power densities remained unchanged. These results suggest that untreated CF anodes could be most promising for enhancing power output in BESs, offering a cost-effective solution for large-scale MFC applications.

Structural and antibacterial evaluation of copper, silver, and bimetallic silver/copper nanoalloys synthesized in chitosan biopolymer

Silver nanoparticles (AgNP) have been used as an alternative to microbial resistance. Nevertheless, AgNP high cost and moderate toxicity to humans limit their use. Copper nanoparticles (CuNP) emerge as an alternative, but their fast oxidation hampers large-scale use. In this scenario, this work propose the synthesis optimization of Ag, Cu, and bimetallic Ag/Cu nanoparticles in a chitosan aqueous solution using factorial design statistics. UV-Vis spectroscopy, zetasizer, and transmission electron microscopy (TEM) measurements demonstrated that the optimized synthetic procedure formed highly stable and monodisperse nanoparticles. X-ray diffraction (XRD) confirmed the nanoparticle's crystalline structure and indicated the presence of an oxide state in CuNP. In addition, X-ray photoelectron spectroscopy (XPS) measurements confirmed that this oxidation occurs at the CuNP surface level. Considering Ag/CuNP, Rietveld refinement of XRD diffractogram demonstrates the formation of an unusual and novel Ag/Cu nanoalloy structure, which was possible due to the metallic ion chelation to chitosan nitrogens before and during nanoparticle growth. In addition, silver presence in the nanoalloy inhibited copper oxidation through an electromigration mechanism. Comparing CuNP, AgNP, and Ag/CuNP, it was possible to reveal the microbicide abilities of the nanoparticles against both Gram-positive and Gram-negative bacteria, emphasizing that the Ag/Cu nanoalloy is a viable option due its high antimicrobial activity and colloidal stability. Therefore, the rational design allowed the synthesis of highly stable NP in the chitosan matrix which exhibited strong antimicrobial activity, indicating that Ag/Cu nanoalloys can act as the next-generation nanomaterials for pathogenic microorganism inactivation.

Green Energy Storage: Chitosan-Avocado Starch Hydrogels for a Novel Generation of Zinc Battery Electrolytes.

Meeting the ever-increasing global energy demands through sustainable and environmentally friendly means is a paramount challenge. In response to this imperative, this study is dedicated to the development of biopolymer electrolytes, which hold promise for improving the efficiency, safety, and biodegradability of energy systems. The present study aims to evaluate hydrogels synthesized from chitosan biopolymer and starch from avocado seed residues in different ratios, and dried using freeze-thawing and freeze-drying techniques. Epichlorohydrin was used as a chemical crosslinker to create a suitable degree of swelling using an ionic solution. Physical freezing crosslinking strategies such as freezing-thawing and freezing-drying were performed to generate a denser porous structure in the polymer matrix. Subsequently, synthesized electrolytes were immersed in 12 M KOH solution to improve their electrochemical properties. The effect of the different ratios of starch in the hydrogels on the structural properties of the materials was evaluated using characterization techniques such as FTIR and XRD, which allowed to confirm the crosslinking between chitosan and starch. The electrochemical performance of the hydrogels is assessed using electrochemical impedance spectroscopy. A maximum conductivity value of 0.61 S·cm-1 was achieved at room temperature. The designed materials were tested in prototype zinc-air batteries; their specific capacity value was 1618 mA h·g-1, and their obtained power density was 90 mW·cm-2. These substantial findings unequivocally underscore the potential of the synthesized hydrogels as highly promising electrolytes for the application in zinc-air battery systems.

Ultrasonic vibration-assisted enhanced antibacterial activity of ZnO/Chitosan bio-nanocomposite

This work delves into biopolymeric membrane-based piezo-catalyst and its effectiveness towards harmful gram positive (E. faecalis) and gram-negative (E. coli) pathogenic bacteria. Conventionally, piezo electric polymers and their modified nanocomposites have been used to eradicate pathogens by their functionality. Maybe first-time bio-compatible polymer (Chitosan) based nanocomposite (ZnO/Chitosan) has been used in this work. ZnO nanoparticle has been synthesized by hydrothermal technique and prepared hydrogel with Chitosan biopolymer. The nanoparticles and its modified counterparts have been characterized by conventional characterization techniques such as XRD, FTIR, FESEM, EDAX, TGA, UV–Vis, PL, Zeta potential etc. The structural assessment via X-Ray crystallography and FTIR validate the successful preparation of the nanocomposite. Electron microscopy, optical and thermal characterizations are used to probe the underlying physical insights of the specimen under study. A detailed examination also revealed that the catalytic process is accelerated by the production of reactive oxygen species particularly OH* during ultrasonic vibration, validated through Photoluminescence spectroscopy. This intriguing outcome led us to apply the piezo catalytic process-which has a drastic bactericidal impact (almost 96 % for E. faecalis and 98 % for E. coli killing after 20 min) and is developing as a substitute antibacterial method to eliminate pathogenic bacteria.

Dielectric characterization of polymer dispersed liquid crystal film with chitosan biopolymer

Polymer Dispersed Liquid Crystals (PDLC) systems were obtained using chitosan as a biopolymer matrix and the nematic liquid crystal (LC) mixture E7 in various concentrations (30, 40 and 50% E7 in chitosan). Several techniques were used to analyze the obtained films: polarizing optical microscopy (POM), IR spectroscopy (FTIR), differential scanning calorimetry (DSC) and dielectric spectroscopy (DS). FTIR spectroscopy revealed minor changes for all PDLC films, suggesting weak interactions between LC and chitosan matrix. For each sample a clear segregation of the nematic droplets could be observed by POM. DSC measurements show that the phase transitions have shifted to lower temperature values for PDLC samples with approximately 2.7 °C compare to pure E7. The values of α (fraction of LC in the droplets) for compositions of 30, 40 and 50 wt% E7 in Chitosan were 0.48, 0.55 and 0.61 respectively, that are lower than for E7/PMMA system.The qualitative and quantitative analysis of the permittivity spectra obtained by DS reveals the fact that there are no significant changes in the molecular dynamics attributed to pure LC E7 compared to the PDLC composites, leading to the conclusion of the existence of a weak interaction between the two components, fact confirmed by the findings from the FTIR results.

Chitosan-photocatalyst nanocomposite on polyethylene films as antimicrobial coating for food packaging

Chitosan (CS), an edible and non-toxic natural biopolymer, has been widely used in food preservation attributed to its intrinsic antimicrobial, biodegradable, and excellent film-forming properties. In this work, we report photocatalyst-loaded chitosan coating on commercial polyethylene (PE) film with enhanced antimicrobial properties for food packaging application. To improve the chemical stability of zinc oxide (ZnO) photocatalyst in acidic chitosan matrix, a thin layer (1–5 nm) of amorphous tin oxide (SnOx) was coated on ZnO nanoparticles. Consequently, the charge transfer efficiency of ZnO is improved and most of the surface defects are retained according to the studies of UV–Vis and fluorescence spectroscopy. The thin SnOx coating on ZnO was observed by high-resolution transmission electron microscopy (HRTEM) and its effects on crystallinity and particle size of ZnO were examined using X-ray diffraction (XRD) and particle sizer, respectively. The addition of ZnO@SnOx particles in chitosan coating increases water contact angle (WCA) and enhances thermal stability of chitosan coating. The antimicrobial activity of chitosan, ZnO-SnOx nanoparticles, and CS-ZnO@SnOx coated PE films were examined against both Gram-negative (E. coli, A. faecalis) and Gram-positive (S. aureus, B. subtilis) bacteria. Compared to the limited antimicrobial effects of chitosan, ZnO-SnOx demonstrates an improved inhibition effect on bacterial growth over 48 h period under light. For the CS-ZnO@SnOx nanocomposite coated PE films, no inhibition zone was observed due to the limitation of disc diffusion method. Meanwhile, there were no bacterial colonies found to develop on the film, rendering this CS nanocomposite coating a good candidate for food packaging applications.

Improved physical, thermal, and biological properties of green synthesized Ag-containing nanocomposites of a novel chitosan-based blend

Different material compositions are being prepared to improve the physiochemical properties of chitosan biopolymer and thus to create new areas of use. This study presents new chitosan(CS)-based products based on synthetic polymers and biosynthesized AgNPs, prioritizing environmentally friendly synthesis methods. Methacrylate-based functional CP copolymer was prepared by the free radical polymerization method. Thanks to the amide, ester groups, and fluorine atoms in the side branch of the CP, a compatible polymer blend (CS-CP) was prepared by the environmentally friendly hydrothermal method through hydrogen bonds with CS. Again, with green synthesis applications, AgNPs were prepared from Prunus spinosa extract by hydrothermal method, and new nanocomposites were produced by adding CS-CPs at different weight ratios. The initial decomposition temperature of 245 °C, which indicates the thermal stability of CS-CP as determined by TGA, was increased to 268 °C with the addition of 7 % AgNPs. Adding CP to CS lowered the glass transition temperature, and this trend continued in nanocomposites with the addition of AgNPs. When CP was blended with CS, the oxidative stress index of CS increased from 18.26 AU to 65.45 AU. It was determined that this oxidative effect increased up to 181 AU when AgNPs were added. Thanks to this feature of the produced nanocomposites, it was found that the MIC (100–250 µg/mL for E. coli, 250–500 µg/mL for S. aureus and for 500–1000 µg/mL C. Albicans) values of CS against microorganisms decreased, and the antimicrobial activity increased. In addition, in studies with cancer (A549 and G361) cells, it was determined that even at low (25 µg/mL) doses, nanocomposites that included 5 % and 7 % AgNPs in their formula had anticarcinogenic activity. Further studies on biocompatibility may be recommended to confirm possible commercial benefits from the materials produced in future research.

Application of Chitosan Nanoparticles in the Adsorption of Heavy Metals from Wastewater: A Concise Review

The biopolymer chitosan is a biodegradable, biocompatible polymer that has been scientifically proven to be an efficient organic compound for the adsorption of heavy metals from a variety of industrial wastewater. Heavy metals are toxic and can cause a variety of harmful health effects, even in low concentrations. Therefore, it is important to remove them from the wastewater to ensure the water is safe for consumption and other uses. Chitosan is a superior adsorbent because it contains functional groups like hydroxyl and amino. Nano-chitosan can be fabricated using various methods but modern nanotechnology research focuses on developing highly efficient and cost-effective green technology. The remarkable physicochemical features of nano-chitosan make it suited for usage in enhancing the durability and washability of textile supplies as well as giving them antibacterial capabilities.

Preparation and Characterization of Chitosan from Schistocerca Gregaria (Desert Locust)

The current study prepared and characterized chitosan from Schistocerca gregaria (Desert Locust) by a chemical method. The Schistocerca gregaria (Desert Locust) chitin and chitosan have yield of 42% and 43% with acceptable physicochemical properties such as Moisture content: 6.0±0.014 and 5.0±0.007 %, Ash content: 2.20 and 2.0%, Protein content 12.0±0.028 and 9.01 ±0.021, Crude fibre8.95±0.041 and 8.95 ± 0.014%, Lipid content, 10.0 ±0.014 and10.0 ±0.014%, however, high carbohydrate, 60.5±0.01 and 65.0±0.01% are quantified in the obtained chitin and chitosan. properties of chitosan prepared were compared with that of the other sources chitosan extracted, the study revealed that (FTIR) analysis confirmed the structure of chitosan by the presence of their characteristic IR bands such as the N–H and O–H stretching bands around 3630 cm−1, oxygen stretching (C-O-C) glycosidic linkage bands around 1125 cm−1, (C-O) in primary OH group bands around 976 cm−1, and 1634 cm−1 corresponding to the free amino group (−NH2) at C2 of glucosamine with 69% degree of deacetylation. Also, the obtained XRD peaks were around 19.01, and 20.48◦ which indicated the amophores structure. This indicates the successive formation of chitosan biopolymer. Therefore, the Schistocerca gregaria chitosan can be said to be of better quality and hence can replace commercial chitin and chitosan in terms of utilization and applications.

A novel Chitosan-Barbituric acid hydrogel supersorbent for sequestration of chromium and cyanide ions: Equilibrium studies and optimization through RSM

The objective of this study is to transform chitosan biopolymer by crosslinking with barbituric acid into an amine-rich product that could be applied as a water treatment agent. Chitosan-barbituric acid (CBA) was synthesized by lyophilization process and characterized using FT-IR, XRD, TGA-DTA, SEM-EDX, BET surface area and BJH pore size distribution analysis. The pHpzc was found to be 7.7 indicating applicability towards both cations and anion adsorption. The CBA was used for seizure of CrVI and CN– from aqueous solutions in batch adsorption as well as fixed bed column experiments. Response surface methodology (RSM) was used as a statistical tool to optimize the functioning parameters resulting in more than 90 % removal of these ions. As shown by isotherm and kinetics data, Langmuir isotherm and pseudo second order kinetics exhibited a good fit for the adsorption process. The maximum adsorption capacities of CBA towards CrVI and CN– evaluated using Langmuir isotherm fitment were 534.75 mg g−1 and 251.66 mg g−1 at pH 4.0 and 6.0 respectively. Thermodynamic studies indicated spontaneous and enthalpy driven course with large negative enthalpy changes of −56.39 and −31.81 kJ mol−1 respectively. Fixed bed column studies showed that the material could be used for larger sample volume treatment even at 200 mg/L CrVI and 100 mg/L CN−1 concentration. Regeneration studies of adsorbent was conducted over five adsorption–desorption cycles with removal efficiency more than 50 %indicating reusability of the adsorbent. Analysis of adsorbent sustainability revealed that the synthesis was eco-friendly as indicated by low value of E-factor of 0.32.

An antibacterial nanoclay- and chitosan-based quad composite with controlled drug release for infected skin wound healing

Microbial infections of surgical sites and other wounds represent a major impediment for patients. Multifunctional low-cost dressings promoting tissue reparation while preventing infections are of great interest to medical professionals. Here, clay-based laponite nanodiscs (LAP) were loaded with the antibacterial drug kanamycin (KANA) before being embedded into a poly(lactic-co-glycolic acid) (PLGA) membrane and coated with the biopolymer chitosan (CS). Results indicated that these biocompatible materials combined the excellent capacity of LAP for controlled drug release with the mechanical robustness of PLGA and the antibacterial properties of CS as well as its hydrophilicity to form a composite highly suitable as an infection-preventing wound dressing. In vitro, PLGA/LAP/KANA/CS released drugs in a sustainable manner over 30 d, completely inhibited the growth of infectious bacteria, prompted the adhesion fibroblasts, and accelerated their proliferation 1.3 times. In vivo, the composite enabled the fast healing of infected full-thickness skin wounds with a 96.19 % contraction after 14 d. During the healing process, PLGA/LAP/KANA/CS stimulated re-epithelization, reduced inflammation, and promoted both angiogenesis and the formation of dense collagen fibers with an excellent final collagen volume ratio of 89.27 %. Thus, multifunctional PLGA/LAP/KANA/CS made of low-cost components demonstrated its potential for the treatment of infected skin wounds.